Author
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Darrah, Larry |
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Submitted to: Agronomy Abstracts
Publication Type: Abstract Only Publication Acceptance Date: 11/2/1995 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Stalk lodging counts in maize (Zea mays L.), even over several locations, provide relatively poor data for making selections to improve standability. Variables of wind gusts, soil moisture, adjacent plots (differing plant heights), and differences in susceptibility to stalk pathogen and insect pests increase genotype environment variation reducing selection effectiveness. This paper contrasts the effectiveness of stalk crushing strength and rind penetrometer resistance for improvement of stalk strength. Stalk crushing strength is a destructive measure, with sampling usually 2-3 wk after flowering. Equipment costs are in excess of $7500. Steps include harvesting of the second internode above ground level, drying stalk samples for 6-8 wk, cutting of 5 cm sections from the internode, and crushing sections vertically in a hydraulic press. Separate plantings are needed for crushing strength and yield data. Rind penetrometer resistance is non-destructively sampled in the internode below the ear and uses equipment costing under $800. Effective selection can be done just before flowering permitting recombination of selected plants or progenies. Average direct gain in stalk crushing strength from six cycles of selection in two populations was 8.6%/cycle, whereas gain in stalk crushing strength in a single population selected by rind penetrometer resistance was 7.2%/cycle. Direct response to rind penetrometer selection was 8.0%/cycle. Changes in ear height and number of days to flowering favored rind penetrometer selection. |
